Attorney-General John Rau has admitted there are fundamental problems with WorkCover.

The workers' compensation scheme in South Australia covers 430,000 employees in 50,000 businesses.

It has unfunded liabilities of about $1.4 billion and achieves one of the lowest return-to-work rates in the nation.

Mr Rau said a new board and structure were needed and changes would be announced in December.

"The actual scheme, the WorkCover scheme from the perspective of the workers who are on the scheme, from the perspective of employers who are paying money into the scheme, from the perspective of everybody who has to use the scheme is buggered," he conceded.

Opposition treasury spokesman Iain Evans backed Mr Rau's assessment.

"We agree with them, get on with it, they've absolutely messed this system up, they should replace the board as soon as they can and the act needs to be rewritten," he said.